The purpose of this study is to determine nuclear magnetic resonance (NMR) spectral patterns of amniotic fluid and to correlate these patterns with the development of fetal lung maturity. The ability to predict maturity of fetal lungs is desirable in a variety of clinical settings when the early delivery of a fetus may be necessary. These situations are not always overt emergencies and allow some discretion in the exact date of delivery. Respiratory distress syndrome in the neonate can be avoided if the maturity of the fetal lungs can be determined in advance and delivery planned accordingly. All of the methods currently available to make this determination require an invasive procedure to obtain amniotic fluid for chemical testing. While these tests can predict pulmonary maturity when positive, negative tests do not mean that respiratory distress syndrome will necessarily develop. In a certain number of cases delivery is therefore needlessly delayed leaving the patients exposed to the consequences of continuing with a complicated pregnancy. Since the NMK spectral patterns of amniotic fluid should change as a result of the biochemical changes which accompany lung maturity, the following investigation is proposed. Amniotic fluid will be obtained through splitting samples withdrawn from patients who require amniocentesis as a part of their regular medical care. The current standard method for establishing fetal lung maturity on amniotic fluid, the determination of the lecithin/sphingomyelin (L/S) ratio by thin layer chromatography, will be performed. In addition proton NMR spectroscopy will be performed, using water suppression, to develop spectral patterns for correlation with fetal lung maturity and the standard L/S ratio. Carbon and phosphorus NMR spectral analysis will also be attempted. Actual lung maturity will be determined by the presence or absence of respiratory distress syndrome in the neonate. It is hoped that NMR spectroscopic analysis will provide data with predictive values for fetal lung maturity superior to the L/S ratio. While this alone would be worth while it would also pave the way for relatively rapid, noninvasive, in-vivo testing using NMR imagers which also have spectroscopic capabilities.